HT4100 4.1, 4.5, 4.9 Discussion, Bad A/C Delco Waterpump. 91 Eldo 4.9 Anything better than AC Delco Waterpumps? in Cadillac Engine Discussion; Originally Posted by cadchris
THE RECLUSE: What pump did you have that only lasted 10K?
As I mentioned before, if ...

As I mentioned before, if anyone hasn't replaced their original tensioner, best to replace it with the new Gates design tensioner to try and prevent bearing failures in ALL componants in the accessory drive. (Alt, W.P., P.S. Pump, Idler.)

From my research, and own experiance, I can only wonder if in fact the failing tensioner caused all my problems of a failed P.S. Pump Bearing, Alt Bearing, and WaterPump Bearing on a new waterpump that was replaced as preventative maintanance all within a a year or so.

I second cadchris' idea on replacing the OEM tensioner with the Gates tensioner/pulley on the 4.9. You wont need the OEM range indicator/dust cover with the Gates, and it will make a huge difference along with a new Gates serpentine belt, $26 at Carquest.

Has anyone here ever had a tensioner apart? I have, and all there is a composit bushing and a spring in there. I had to take one apart to get my plater to polish and chrome plate it. And there should be a very small amount of grease on the bushing surfaces.

I tried to go 3-4 sizes bigger on the belt to lessen the tension on the drive belt system in order to buy more time, but it finally started to leak coolant out the weep hole, and the main bearing got extremely noisy.

I missed out on that discontinued Craftsman Digital Torque Meter on E-bay to do some torque comparisons of the Gates Tensioner vs. an old style GM Tensioner so I could post some pics if there was a big difference but I wanted to see if there is much of a difference in tensioner specs just for the h'll of it. Hopefully I can find that meter on e-bay again.

I asked someone a few weeks ago who's a vendor at the APPEX Show in Vegas, to stop by the AC Delco booth to see if they could get some contact info or a backdoor into Delco Engineering so I can find out what they know about pump failures and inferior bearings/seals they are sourcing which I believe everyone in the aftermarket is also sourcing from the same place in Asia on all these pumps.........just a feeling I have.

This summer, I researched the 6 superseded OEM part numbers and started to track down original Cadillac GM boxed OEM pumps and the early Delco replacements date stamped from the early 90's and on. I'll post that info some day but I have many more calls to make of who has these old better made pumps.

I'm still hoping other 4.9/4.5 owners can give some feedback of either good or bad pump experiences with Delco or other mfgs in the aftermarket and what years they were installed so a better picture can be made of good or defective pumps from year to year.

I believe that somewhere around the early 90's the better made GM boxed pumps were discontinued then Delco picked the up the line and were also high quality since they would've been made to replace failures under factory warranty. My feeling is that the Delco pumps date stamped from the mid-90's to early 2000's were the better made pumps. I even spoke to an old AirTex tech who confirmed my belief of one pump I ran across this summer that had the letter "A" in a "circle" stamped on the cover which was much different from other Delco Pumps. He said AirTex was actually making the pumps here in the U.S. with U.S. components for GM and Delco, "back in the day" and were stamped with the letter "A" in a "circle" on the front of the pump. But this dealer also sent me a photo and I could tell someone sandblasted and re-painted it so I fwd the photo to this AirTex Rep. and he said the same, so something was up with that old pump and it was probably a return or the dealer did it to re-sell for some reason!

I did find some orig. boxed GM Cad. pumps but they were also over $350!

I'm still considering the electric water pump retrofit from that Australian Company Davis Craig but I'll still have to puton another new replacement pump and cut the impeller off for better flow with the electric pump and re-rout the beltdrive with a smaller belt. The fitment down by the lower hose is going to be very tight and they said the pump can be put in the upper hose, but if there is a coolant loss, it will no longer pump. They also sell a low coolant alarm and I also researched other company's who make these devices which I would need if the pump was put in the upper hose.

I now know that I'll have to also do the front cover gasket and I'll need a new lower water housing inlet due to rust and I may as well do the timing chain too.

I again warn anyone looking to replace a good working OEM pump for preventative maintanacne NOT TO DO IT. If you have an orig. pump, it's much better than the new pumps made today that seem to fail every year or so........!

I've cleaned my cooling system out well with the old GM Flush Procedure using the long discontinued
Prestone AS-100 2 part Oxalic Acid w/ Sodium Carbonate neutralizer. There is a whole TSB flushing procedure on it. It's still available at some GM dealerships, under GM part#12346500.

I was going to do a write up on it here some day of this old lost procedure so others can decide on using this procedure or the junk they now sell at the parts store that doesn't work, but I figure it would cause a whole "flushing procedure controversy"!

Anyone interested should Google: "Prestone AS-100 or AS100 or GM TSB part#12346500" to learn more. Or just buy "Wood Bleach" from ACE Hardware and Arm & Hammer Washing Soda in the yellow box from the grocery store.......all the same stuff and concentrate since I discussed the old Prestone MSDS with the mfgs chemist of the ACE Woodbleech at "Savogran Chemical.
Here's the stuff here: http://www.savogran.com/Information/Wood_Bleach_PD.pdf

Here's a detailed link from the Vette Forum with the GM TSB Procedure which is also all over the web in other forums.........this is the only way to really flush out a system to get it so clean it will maybe leak, but hey....that's what the GM/Bars leak Tabs are for including the other multi-step sealers + I always do oil analysis to monitor engine coolant in the oil :http://forums.corvetteforum.com/c4-t...ol-sludge.html

I've also put some woman's nylons in the upper hose to trap any scale/rust in the system and was even considering installing a coolant filter like the diesels have just to be sure.......and to rule out an internal coolant chemistry problem, I'm also going to send the coolant out to be analysed to see if there is indeed an issue that could cause the pumps to fail but I know it's just crumby Asian made pumps/seals/bearings.

I'm also looking into putting some Zinc and Magnesium sacrificial anodes in just for the he'll of it....cheap insurance.

You can't go wrong with Carquest OE replacement water pumps. Parent company is Japanese, with subsidiary companies in US. Pump is manufactured in either Canada, Mexico, or US. Replaced mine on the 4.9 92 Eldo one year ago, no leaks, and no issues.

Also, can't recommend Gates Drive Align premium belt tensioner assembly strong enough. I noticed the size and shape difference from the OEM assembly and paused before committing to it, and have no regrets, as well as the Gates Serpentine belt as a much better assembly than what GM used at the factory.